process rotate uses a comprehension instead of a loop

Author: arekbulski

kaitaistruct.py

@@ -361,8 +361,8 @@ def process_rotate_left(data, amount, group_size):
         if amount == 0:
             return data
 
-        r = bytearray(data)
         translate = KaitaiStream.precomputed_rotations[amount]
-        for i in range(len(r)):
-            r[i] = translate[r[i]]
-        return bytes(r)
+        if PY2:
+            return bytes(bytearray(translate[a] for a in bytearray(data)))
+        else:
+            return bytes(translate[a] for a in data)